Phone Battery Boosters: What's Your Solution?

Between Wi-Fi, 3G, 4G, bigger screens, brighter games and busier lives, there's a lot taxing the battery in your smartphone right now. Thankfully, there are a lot of options when it comes to keeping the juice flowing. Which strategy do you use?
There's no real one-size-fits-all approach that'll suit everyone; I'm interested to hear what approach Giz readers regularly take, and why. Here's my take on each of the options you can take

Cheap and cheerful: The Extra Plug

Pros: It's definitely cheap; all you need is an additional plug to provide power to your phone or tablet -- and for most of the phones on the market, that can be the same Micro USB plug for many devices. When connected to a power plug, you're also looking at a dedicated power supply that's unlikely to run out and doesn't require its own charging
Cons: There's pretty much no portability to the plug approach; what you're doing is tethering your device to a power socket, rather than being able to move around while charging your gadgets. Power plugs need power cords, and their natural state is to tangle around everything they can; bags, other cords, throats, etc. If you're carrying a plug in your bag, it'll also have prongs that can stab into other items in your bag -- or along the screen of your favourite tech gadgets.

Slightly Less Cheap: The Extra Battery

Pros: An extra smartphone battery neatly sidesteps the problem of having to be tethered with a plug; if you're running low on power you simply slide out the flat battery and replace it with your sparkly freshly charged power unit.
Cons: It used to to be an Apple exclusive problem that you couldn't get a battery for a sealed system, but recent releases from most other manufacturers have included models with sealed batteries, including the very appealing HTC One X. There's also the issue of keeping the additional battery charged; you've either got to put it in the phone to do so, or splash out extra cash for an external charging device. Forget to recharge the flat battery, and all you're doing is carrying around a lump of plastic and metal, too.

Highly Flexible: Battery Power Packs

Pros: There's no shortage of multi-charging units, and the appeal here is quite simple; most of them connect out through USB, and that means you can use them to charge all kinds of portable gadgets.
Cons: There's a tradeoff here between size and portability; smaller battery power packs don't carry as much charge, but the larger units make a significant dent in your bag. Depending on the scope of your travel, there can also be interesting discussions to be had with airport security staff, as many limit the number of batteries you can travel with.

Highly Portable: Dedicated Battery case

Pros: A dedicated battery case gives you a double hit; a protective case for your smartphone investment along with improved battery life to keep you going for a lot longer than a standalone model.
Cons: You're limiting yourself to a single phone model, unless you're lucky enough for a vendor to keep the exact same shape for its upgrades.
Image: beaugiles

For on the go use, I've burnt (in one case quite literally) through a few power packs over the past couple of years -- what's your smartphone charging solution?